Governor Deval Patrick’s push for a $1.9 billion tax hike last week is a bold — his critics call it overreaching — attempt to go out of office with a final crescendo that will define his record as governor, political observers say.

But the plan also carries with it the risk of failure and potentially builds political peril for his fellow Democrats who, unlike Patrick, will face voters in next year’s election.

The outcome of Patrick’s move is far from clear, though it has quieted chatter that the governor intended to endure a lame-duck status in his final two years before moving into the private sector.

In an interview, Patrick sloughed off suggestions that his push for a tax hike from 5.25 percent to 6.25 percent to fund transportation projects and education programs would create political chaos, or that his proposals were legacy driven.

He said his decision was fueled by what he sees as a unique chance to use the political influence he has gained to do something he believes is critical to the state’s future.

Jim Davis/Globe Staff/File

“I obviously strongly disagree with what he is proposing, but you are the governor and you have the power, shouldn’t you do what you think is right?’’ said Paul Cellucci, an ex-governor.

“As a relative newcomer to this line of work, I see people spending a lot time accumulating political capital but not much time spending it,’’ he said in an interview with the Globe. “For me, what is the point of having political capital if you can’t use it for the greater good?’’

Aides said Patrick’s decision to push for a sweeping plan in the twilight of his tenure should not come as a surprise, given that he has struck themes of raising tax revenue to pay for infrastructure projects and programs since his 2006 gubernatorial campaign.

“He’s talked ever since he got in that first race of making these kind of investments,’’ said Doug Rubin, his chief political adviser. He said Patrick waited until his final two years because of economic constraints and the prolonged recession.

Another aide, who did not want to speak publicly, said that during deliberations over the details of the plan, Patrick rejected advice that he scale back the size of the tax hikes in order to make it more politically acceptable.

The governor, the aide said, insisted they ignore potential political consequences and focus on putting forth a plan that fit his vision.

A nearly audible sigh of relief came from his office when legislative leaders did not declare his proposal “dead-on-arrival,” an oft-used term on Beacon Hill for governors’ sweeping budget plans, particularly those with big tax hikes.

Indeed, the way he packaged the tax plan could make it easier for key legislative blocs to accept. By lowering the sales tax to 4.5 percent from 6.25 percent, the plan will be attractive to the border communities, particularly in the Merrimack Valley, where there is stiff resistance to sales tax hikes as they compete with retailers in New Hampshire, which has no sales tax.

His plan would further restructure the income tax by doubling personal exemptions, a change that would benefit people at the lower end of the income scale, while putting a heavier burden on those at the top. That plays to Patrick’s long-standing desire to make the state income tax more progressive.

It also opens him up to a challenge from fiscal conservatives, who cite state Supreme Court rulings that prohibited the creation of a graduated tax.

But Paul Watanabe, the chairman of the political science department at the University Massachusetts Boston, said Patrick’s risk is reduced because the House and Senate are heavily dominated by the Democrats who will protect him from any political embarrassments.

“He is unburdened of having to face the electorate and relieved of any political accountability,’’ Watanabe said.

But Senate President Therese Murray was noncommittal about her support Wednesday. “He threw long, and maybe we’ll meet him somewhere down the road,” she said after the speech.

In the days after Patrick announced his decision to push a controversial and sweeping agenda, the proposal won plaudits — and drew some warnings — from those who have watched Beacon Hill for some time.

“Why shouldn’t he be bold?’’ said Michael S. Dukakis, the only previous governor in modern history who declared himself a lame duck two full years before the end of his term. “What is your legacy? Your legacy is doing everything you can do that you think is right and help build a better future for your state.”

Even a former Republican governor, Paul Cellucci, a strong antitax chief executive, said Patrick should use what influence he has left to pursue an aggressive agenda.

“I obviously strongly disagree with what he is proposing, but you are the governor and you have the power, shouldn’t you do what you think is right?’’ said Cellucci, who initiated a successful ballot petition in 2000 to cut the state income tax to 5 percent. It was eventually blocked by the Democratic Legislature.

But Rob Gray, a Republican political strategist and former Cellucci adviser, said Patrick is putting not only his legacy on the line, but also threatening the Democrats’ iron grip on Beacon Hill if the lawmakers are forced to vote on the massive tax package.

“It may be a bold move, but politically not popular,’’ Gray said. “You could call it a selfish move because if he were running for reelection, Governor Patrick wouldn’t do this. By proposing it, he’s potentially parking the hearse at the door of Democratic candidates and the legislators who will be on the ballot in 2014.”

Gray also said Patrick’s legacy could well be remembered for the size of the tax increase and less for the transportation projects and education programs that are established.

“If he gets his way, it would establish him as the governor who has passed the most tax increases in over 40 years,’’ said Gray, noting the governor’s approval of a hike in the sales tax in 2009. “He just may go down as the most tax-happy governor of Massachusetts in recent history. Most people would not want that legacy.’’

Rubin argues that voters are more sophisticated and discerning than what the Republicans argue. He said Patrick comes across as a governor acting out of principle, not for political gain.

“The people of Massachusetts have shown that candidates who stand up for what they believe and put the interest of the state first have a lot of success,’’ Rubin said. “I don’t buy the premise that this is something that hampers Democrats going forward.’’

The governor’s move fueled speculation that he was setting himself up for a future run for office, including for president. But Patrick, who was general counsel to Coca-Cola before running for governor, has made it clear that he does not have further political ambitions and plans to return to the private sector.

A chance to leave his mark through a signature tax proposal, however, was clearly on his mind during his State of the Commonwealth speech Wednesday.

“As I consider our work for the last years,” he told lawmakers in the House chamber, “I think most governors wonder ‘What will last?’ ”